The Unbiased Truth about Artificial Sweeteners | Chris Kresser

The Unbiased Truth about Artificial Sweeteners

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These three wooden scoops show different forms of sugar and artificial sweeteners.
Artificial sweeteners come in many forms, but are they good for you? Find out. iStock/MamaMiaPL

Note: This article was originally published in 2014 and was updated in 2018 to include the latest research. Several years ago, the evidence was limited, and I was hesitant to make a firm conclusion on the dangers of artificial sweeteners. However, I now believe there is sufficient evidence to suggest that artificial sweeteners should not be included in a healthy diet.

Artificial sweeteners continue to be a controversial public health issue, and the research keeps coming. On one hand, many people are adamantly opposed to the use of sweeteners like aspartame, sucralose, neotame, acesulfame potassium (Ace-K), saccharin, and advantame because of the purported link with increased risk for cancer and other diseases. But on the other hand, they’re becoming increasingly popular as people try to reduce calorie consumption and lose weight.

There’s too much research out there to cover comprehensively in a blog article, but I’ll try to include the basics: Will artificial sweeteners give you cancer or other diseases? Do they actually help with weight loss? And ultimately, should you be eating them?

To learn all about sweeteners—natural and artificial—download this free eBook today.

The research on artificial sweeteners has always been lacking—until now. So, are artificial sweeteners healthy? Find out in this article, updated in 2018 with the latest information. #nutrition #wellness #chriskresser

Will Artificial Sweeteners Give You Cancer?

Artificial sweeteners were first tied to cancer risk in the 1970s after a study showed that a combination of saccharin and cyclamate (another early artificial sweetener) caused bladder cancer in lab rats. The mechanism behind these effects was later found to be specific to rats and not generalizable to other animals or humans (in these rats, comparable doses of vitamin C can also cause bladder cancer), and further studies demonstrated that neither sweetener is carcinogenic. (12)

However, this study cast a shadow of doubt over artificial sweeteners, and thanks in part to the media’s penchant for blowing nutritional headlines way out of proportion, the reputation of artificial sweeteners has never recovered.

A later study suggested a link between aspartame consumption and brain tumors. The authors based this hypothesis on the fact that both brain cancer and aspartame consumption had increased since 1980—despite not knowing whether the people getting brain tumors actually consumed artificial sweeteners—and on a rat study where aspartame-supplemented diets led to the formation of brain tumors. (3)

This association has been more or less dismissed by the research community because three case-control studies have found no association between brain tumors and aspartame consumption, and subsequent animal studies haven’t been able to replicate the aspartame-induced brain tumors found in the original rat study. (4)

Artificial sweeteners have also been implicated in the development of lymphoma and leukemia, and one observational study found a weak link between artificial sweetener consumption and development of non-Hodgkin lymphoma and multiple myeloma in men, but not in women. (5) The study authors concluded that due to the inconsistency in their results, there isn’t likely a causal link, although it can’t be ruled out.

Artificial sweeteners have also been tested for associations with other cancers, including breast, pancreatic, stomach, colon, and endometrium, with no correlations found. (6)

Based on the evidence, I don’t think artificial sweeteners are a huge risk factor for cancer, although the possibility can’t be ruled out and caution is warranted.

Artificial Sweeteners Can Change Your Metabolic Health

Artificial sweeteners have also been tied to an increased risk for developing metabolic syndrome and related diseases such as diabetes and cardiovascular disease. Numerous observational studies have attempted to parse out a consistent association with disease risk, but for every study that has linked artificial sweetener consumption with metabolic syndrome, heart disease, or diabetes, there’s another that has found no association. (789)

Fortunately, we have meta-analyses, which serve to pool together similar studies and try to determine the overall effect. In July 2017, the Canadian Medical Association Journal published a meta-analysis that picked apart the findings from seven randomized controlled trials (RCTs) and 30 cohort studies on artificial sweeteners. (10) In total, the studies followed more than 400,000 people for about 10 years.

In the RCTs, artificial sweeteners had no significant effect on cardiovascular or metabolic disease risk. However, in the long-term cohort studies, consumption of artificial sweeteners was associated with a higher incidence of type 2 diabetes, metabolic syndrome, and cardiovascular events, even after controlling for confounding variables.

Of course, observational studies cannot confirm causality, but another study, published in the journal Nature, showed that artificial sweeteners altered the gut microbiota and that this was causally linked to glucose tolerance in mice. (11) For the humans included in the study, even just one week of artificial sweetener consumption was enough to reduce glucose tolerance in half of the participants.

It’s clear that artificial sweeteners can have an impact on your gut microbiota—and that can have far-reaching effects on your health.

For a complete breakdown of how this works, check out my 2016 article “How Artificial Sweeteners Wreak Havoc on Your Gut.”

Pregnant Women: Avoid Artificial Sweeteners, Just to Be Safe

There has been concern in recent years over a potential link between artificial sweetener consumption and pre-term delivery, prompted by two observational studies published in 2010 and 2012. (1213)

These studies have significant limitations:

  • The associations are small and not linearly dose-dependent;
  • Not all artificially sweetened beverages were accounted for; and
  • Women who consume more artificially sweetened drinks also tend to smoke more and have higher BMI and lower socioeconomic status. (14)

All told, the risk seems small, but I would advise pregnant women to avoid artificial sweeteners just to be on the safe side.

The Big Question: Do They Help You Lose Weight?

For most people, the primary motivation for consuming artificial sweeteners is a desire to eat fewer calories and lose weight. But do artificial sweeteners actually help achieve that goal? Yet again, the evidence is mixed.

Many observational studies have found a positive association between artificial sweetener intake and obesity, but in this situation, reverse causality is particularly likely. (15161718) In other words, while it’s possible that artificial sweeteners contributed to weight gain in these studies, it’s also possible that people who are overweight are more likely to choose diet beverages and other artificially sweetened foods in an effort to lose weight. We also have a decent number of clinical trials testing the weight loss effects of artificial sweeteners in humans, although many are too short term to have much practical significance.

In one study, overweight subjects were given supplements of either sucrose or artificial sweeteners for 10 weeks. (19) At the end of the trial period, subjects in the artificial sweetener group had experienced, on average, a reduction in weight, fat mass, and blood pressure, while subjects in the sucrose group gained weight and had increased blood pressure.

A study published in 2014 on weight loss and artificial sweeteners was surprisingly positive: over a 12-week period, participants who were instructed to drink 24 ounces of artificially sweetened beverages every day actually lost more weight than participants who were instructed to drink 24 ounces of water daily. (20) (It’s worth noting that this study was fully funded by the American Beverage Association.) Other trials have also shown successful calorie reduction and weight loss in participants who consumed artificial sweeteners (usually in the form of beverages). (212223)

So what do we make of all this? Fortunately, the same meta-analysis I mentioned above of over 400,000 people also looked at weight loss. (24) When they pooled together the seven RCTs, they found no significant effect of artificial sweeteners on body mass index (BMI). On the other hand, when they pooled the cohort studies, consumption of artificial sweeteners was positively associated with increases in weight, waist circumference, and a higher incidence of obesity.

Based on this evidence, it seems that artificial sweeteners do not necessarily lead to weight loss, and may in fact do the opposite!

As I mentioned, artificial sweeteners’ ability to disrupt the gut microbiota can lead to weight gain, but that’s not the only mechanism involved here. These sweeteners can actually “confuse” your body and make it harder for you to shed extra pounds.

How These Sweeteners “Confuse” Your Body

For most of human history, sweeteners were inextricably tied to caloric density. Our sweet taste receptors evolved primarily to help us identify calorie-rich food sources. So imagine the confusing results when our taste receptors are bombarded with sweetness without that expected surge in calories.

Animal models certainly indicate that artificial sweeteners can impair the innate ability to regulate caloric intake. Rats who are fed with artificial sweeteners consistently gain more weight than rats who are fed with glucose or sucrose. (2526) Additionally, the rats don’t tend to lose the excess weight, even after their diets are switched back to glucose or sucrose to reestablish the normal connection between a sweet taste and calorie-rich foods.

Interestingly, rats who were given stevia solutions gained significantly more weight than the glucose-fed rats and similar amounts of weight to the saccharin-fed rats. (27) Rats fed with artificial sweeteners also develop an impaired ability to respond to sugar-containing foods. In one study, rats who had been fed artificial sweeteners were unable to compensate for the calorie content of a sugar preload by eating less chow afterwards, while rats who had been fed sugar-containing food compensated almost perfectly for the extra calories in the preload by eating less chow. (28)

Rats that have been conditioned with saccharin also display a reduced thermic effect in response to consumption of a caloric sugar-containing meal, as well as higher blood glucose, compared with rats who had been conditioned with glucose. (2930) Additionally, saccharin-fed rats secreted less GLP-1 (which is implicated in satiety and glucose homeostasis) when given a sugar-containing test meal. (31)

Unfortunately, although the animal evidence is fairly robust, evidence in humans is limited. However, two interesting studies that used MRI to measure brain responses to sucrose solutions indicate that artificial sweeteners may alter the brain’s response to sweet tastes in humans. In one study, people who regularly consume artificially sweetened drinks had higher reward responses to both saccharin and sucrose compared with people who don’t consume artificial sweeteners. (32)

Additionally, people who don’t consume artificial sweeteners had different brain responses to the saccharin and sucrose, while those who regularly consume artificial sweeteners responded the same to both sweeteners. Another study found that the amygdala’s response to sucrose consumption was inversely related to artificial sweetener use. (33) (The amygdala is part of the brain that is involved with taste–nutrient conditioning.)

Should You Be Eating Artificial Sweeteners?

To sum up, artificial sweeteners are extremely new to the human diet, and for modern, industrial foods, the operating principle should always be “guilty until proven innocent.” We’ve conducted what are essentially population-wide experiments with the introduction of other industrial foods (such as high-omega-6 vegetable oils) because the initial evidence seemed promising, and we can see how well that worked out.

Increasing evidence from animal studies and human observational studies points to a link between artificial sweeteners and an increased risk for:

  • Glucose intolerance
  • Weight gain
  • Diabetes

Observational evidence also suggests a link between artificial sweetener consumption and cardiovascular disease risk.

While we have limited causal evidence in human clinical trials, I believe the evidence is strong enough to conclude that artificial sweeteners should not be included in a healthy diet.

What has been your experience with artificial sweeteners? Do you avoid them? Include them? Share your thoughts in the comments!

In case you missed them, be sure to check out parts one and two of this series.

195 Comments

Join the conversation

  1. My personal experience with drinking artificially sweetened beverages, and getting multiple migraines a week is why I stay away from artificial sweeteners.

    When I was working my way through my first two years of medical school I drank a lot of beverages with artificial sweeteners in them. Mentally I told myself, if I couldn’t work out as frequently, maybe I could at least cut out the calories!!

    This seemed to keep me firmly fixed in front of my medical textbook, however I started to experience multiple migraines a week. This would ruin the studying time because I required rest in a dark room to get rid of the ridiculously bad headache. Instead of suffering from these, I decided to look at what I was eating and drinking. I found myself drinking a lot of Sugar-free Red Bull and Rockstar Lemonade. These two beverages both are riddled with various different artificial sweeteners and other stimulants. Once I removed these two beverages from my diet, I have had only one migraine in the past 3 years.

    I know this could be from the other ingredients in each of these beverages, however I am not taking any chances!!

    Since moving away from artificially sweetened beverages I tend to drink unsweetened green tea!!

    Check out my blog RonTorranceDo.wordpress.com about the benefits of green tea.

    • “I found myself drinking a lot of Sugar-free Red Bull and Rockstar Lemonade. These two beverages both are riddled with various different artificial sweeteners and other stimulants. Once I removed these two beverages from my diet, I have had only one migraine in the past 3 years. ”

      Pressor effects of the caffeine?

      • I am still consuming an equivocal amount of caffeine through my consumption of green tea and espresso. I have taken all artifical sweeteners out of my diet as well as almost all added sugars out of my diet. My other independent variables have been fairly consistent.

    • I’m glad you got the success you needed. And although I have read that green tea is wonderful for you, I have been unable to force myself to drink it. Maybe once a year i’ll try it, but I find the stuff tastes nastier than anything laced with aspartame…. which I also avoid.

      And I’m a tea drinker! It’s just NOT gonna be green tea!

  2. Our bodies are natural, whole beings. Thus, we should consume natural, whole foods. Everything in moderation. If one wants to be healthy, eat clean. Eating clean means veggies, fruits, meats, whole grains. Nothing processed. No need to even worry about what sweetener to use if eating clean. Fruits will combat that sweet tooth! If I do need a sweetener, ex. in a cup of coffee, I use Agave Nectar, a natural sweetener which is low glycemic.

    • We use agave nectar even though it has a lot of problems associated with it and is highly processed. This is for my wife’s benefit as she has a very strong corn allergy and any minor exposure means three days of intense migraines for her.

      Mostly we only use it to replace corn syrup when recipes call for it, so consumption is very limited.

  3. I eat sweetener (stevia) because I assume it has little effect on insulin. This article ignores this as a reason for using artificial sweeteners. Low carb dieters will use stevia before honey or maple syrup.

  4. As a Compulsive eater I’ve reduced my intake of artificial sweetners just because of psychological reasons.

    I found that I craved sucrose ladened foods the more diet foods I consumed. If this because of lower nutrition density (likley) or just ’cause I’m a compulsive eater nut job who has a sugar addiction is not relevant to me personally.

    I simply do better eating less sweet tasting foods.

    Note: down 96 pounds since October 22nd 2013 on a Paleo meal plan.

  5. I am disgusted by the attitudes and attacks towards Chris, and other people on this blog that share interests, concerns, questions, and thoughts. No one is saying “I AM TRUTH AND YOU SHOULD LISTEN TO MEEEEEE.” and we’re all in this together.
    Disagree with Mr. Kresser? Go for it, but don’t sit behind your computer and spout out attacks on everything and everyone involved. People are trying to take hold on their lives. Health is everyone’s individual journey, and there is so much conflicting information out there, it’s very difficult for anyone to have a clue as to what to believe. These articles are provided as a service to those who want to read them. Are you people who are so boldly disagreeing and trying to disprove everything on all of these blogs making this much of a stink to corporate sponsored journalists and researchers? are you calling up the researchers who come out with bogus results and ripping their heads off? do you make everyone who asks questions feel like an idiot?

    if so, sorry your life is such a bummer.
    but please, keep your nasty rants to yourself and the miserable people around you. Someone is working to no end to provide incredible information and research for those of us who want to hear it. we all have our own ability to challenge and criticize if we want to. but please, stop attacking the other people who want nothing more but to feel good and understand why.

    Chris Kresser, I appreciate what you do.
    Everyone else, keep asking questions. Keep wanting more.

  6. Just listen to your instincts. artificial sweetners are bad! They do not grow, swim in the sea or graze. if youcrave sweet eat a piece of fruit. if that’s not sweet enough the have a small piece of high calorie but nutrient rich home made chocolate. sweetened with crushed dates or currents ect. The answer is to break the sweet/ craving cycle by not denying your self or with fake food. Once you do this even your cravings for healthy sweets will decline. i did it and have maintained it fir many years

  7. I avoid artificial sweeteners completely. I use stevia sparingly, and have recently become suspicious of even that, as it seems to be causing me reactive hypoglycemic episodes.

    However, my recent Genova Diagnostics NutrEval Plasma Amino Acids profile results showed very elevated levels of aspartic acid (0.99, reference range: .20-.50). Does anyone know what this might be caused by? My doctor was very surprised that I do not drink diet sodas.

  8. Unfortunately all sugar alcohols raise my blood sugar substantially. They may be “natural” compared to sucralose but they are still fairly highly processed.
    The only sweetener I currently use is stevia leaf (which I don’t like too much) and “Just like sugar” which is chicoree based.

  9. I have given up on all sweeteners, including artificial sweeteners. In the pursuit of eating a whole foods diet that is as natural as possible, I don’t see any artificial sweeteners as fitting in, and I do’t care to review any research findings pro or against any of them. I’ve been off all sweeteners for probably 9 months now and I honestly don’t miss them.

    • Another anecdote Matt! One of the side effects that has been suggested for aspartame (Nutra Sweet) is vertigo. Sure enough, this happened to me. Several years ago I started taking a fibre supplement, Metamucil, which contained aspartame. Soon after, I started getting vertigo. The first attack was triggered by a visit to a physiotherapist. He bent my head back and down into a vertical position while manipulating my back, and it suddenly hit me. Then the vertigo kept recurring whenever I tilted my head in the wrong position. I eventually found the possible link with aspartame on the web and switched to another version of Metamucil which has sucrose instead of aspartame, and my vertigo has now completely disappeared.

  10. I fondly remember a cold where I mistakenly bought sugar-free cough-drops. One of these – with Xylitol – managed to give me so much gas that I thought I would explode. I never liked sugar-free before because of the odd taste and since then I take even more care than before. If sweet then sugar.

    • A couple of quotes from Wikipedia on the GI issues with xylitol:

      “In one study of 13 children, four experienced diarrhea when consuming over 65 grams per day.[35] Studies have reported adaptation occurs after several weeks of consumption.[35]”

      “As with other sugar alcohols, with the exception of erythritol, consumption in excess of one’s laxation threshold (the amount of sweetener that can be consumed before abdominal discomfort sets in) can result in temporary gastrointestinal side effects, such as bloating, flatulence, and diarrhea. Adaptation, an increase of the laxation threshold, occurs with regular intake. Xylitol has a lower laxation threshold than some sugar alcohols, but is more easily tolerated than others such as mannitol and sorbitol.”

      And Dr. Ellie at drecoaching.com points out that it’s a prebiotic:

      “Here is a review of one recent study at the National Institute of Health:
      …a beneficial shift in the metabolic patterns of the colon microbes was measured with the tested products. These in vitro studies provide evidence to the prebiotic characteristics… and beneficial properties of xylitol were demonstrated in the colon model.(http://www.ncbi.nlm.nih.gov/pubmed/17995737)

      The only problem with xylitol is when you consume too much too quickly. Then xylitol draws water into the intestine which can cause a temporary digestive inconvenience! This is why large amounts of xylitol should not be eaten all at once until your digestion is conditioned and healthy.”

  11. Chris.What about the effect of different artificial sweeteners on blood sugar & insulin levels? What is your opinion on that ?
    And also the excitotoxicity of aspartame?

  12. Why can’t people , especially Americans learn to curb their depraved taste for sweet tasting foods —–. Problem solved!
    In any case the prime problem appears to be too much food of the wrong kind. Are people digging their graves with their knives and forks, also If it’s packaged beware.

  13. Hi all,
    I’d worried for many years about my overweight husband esp after he became a type 2 diabetic. Then last year I finally convinced him to (mostly) give up his addiction to Equal (aspartame) which he’d used in his thermos of coffee every single morning AND it’s in the diet pop he drinks (sadly he won’t give up the diet pop which he mixes with his rum-sigh). He’s slowly been losing some weight though doing nothing else different ever since I got him last year to switch over to a natural sugar substitute called ‘Just Like Sugar’…
    http://www.justlikesugar.com/

  14. I am a retired neuroscientist. I like sweetener in my coffee and yogurt, so I’ve read everything I can find about the safety of the only 3 that taste good to me: sugar, aspartame and sucralose. It seems that all of them can be hazardous if you consume a lot of them, but all are quite harmless at very low doses. The obvious solution: Use just a little of each. So in my 15-oz. mug of coffee each morning, I use one blue packet, one yellow packet, and one teaspoon of the white stuff (cane sugar). This seems like the most reasonable approach, given the confusing and inconclusive current state of the science. And it tastes fine.

  15. I don’t dismiss non-nutritive sweeteners out of hand. I do keep aspartame consumption to a minimum. Not because of any of the weird things natural-health bloggers say about it but I’m wondering what excess phenylalanine consumption does in someone with one PKU gene or when you overwhelm your breakdown enzyme production, even temporarily. It’s a neurologically active amino acid no matter what your genetic template. I know my head will stop bothering me if I (apparently) overdose on the stuff.

    But every NNS has its own issues and its own story to tell. We *cannot* paint every one with the same brush. Not when we *know* sugar kills. You know, Ebola is “natural” too. Houses are artificial, but they protect us from dying of exposure, even when in bad shape. Something to consider, anyway.

    • Start bothering me. My head *starts* bothering me on too much aspartame. Sorry, no edit available.

  16. Many years ago I tried to use Splenda in my morning coffee every time I went on a “low carb” diet (long before I learned about ancestral ways of eating). I would get terrible migraines every day for about 3 days, and I am not someone that gets migraines very often. I assumed it was by body adjusting to the low carb diet, going through withdrawls. Long story short, it was the Splenda, and I have steered clear of it ever since.

    • Yes, there is a brand called Pur that uses Xylitol for sweetener. I happen to be chewing some at the moment.

      • Just beware of the laxative effect of sugar alcohols such as xylitol and sorbitol. This effect is dose dependent and differs from person to person. People here are forgetting genetic variation and why/how some items effect one person differently from another.

        Also, as to all the rodent studies mentioned in this thread, we know that rodent results do not always translate to identical human results. Pigs make a better human analog that do rodents, but they are more expensive to purchase and house, some people make footballs out of them, etc.

  17. What about the fact that aspartame is 10% methanol in a free form (not bound to pectin) that can cross the blood brain barrier?

  18. ” women who consume more artificially sweetened drinks also tend to smoke more, have higher BMI, and lower socioeconomic status.”

    Wow, how much more data is really needed to convince people that these artificial sweeteners are not healthy?

    • I’m a woman – non smoker, non drug user, almost non alcohol user (rare cocktail at a party). I’m educated, upper middle class, worked all my life and am now retired and writing. And I love my splenda. Most of my peers have the same status. I don’t remember being part of any poll either. hmmm

      • more likely that a low socioeconomic person has a higher BMI and smokes, besides uses artifical sweeteners.
        thats the only point.
        of course educated ppl use them too. alot of MDs smoke. and alot of rich ladies are quite round.
        its a simple correlation. the causation lies in the fact when you quit the crap, health improves. across all classes.

    • Just my opinion, but I think the key here is moderation. If you’re drinking diet soda all day, that’s probably not so good. Your body does need water and water sans chemicals is best. But I don’t believe it means you can’t have a glass of diet soda amongst all the glasses of water.

      • Amen!
        How about anecdotes do not equal double blind, very long term studies, rampant placebo effect, and thinking that honey (combo of glucose, fructose, sucrose) is any different metabolically than refined sugar (sucrose).

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